During some aspects of the completion or workover of a subterranean oil, gas injection or disposal well, particularly in offshore areas, such as the Texas and Louisiana Gulf Coast area, it has been frequently found that the production zones are such that the produced fluid, whether it be oil or gas or mixtures thereof, will carry with it, through the subterranean well conduit and to the top of the well, solid matter, commonly referred to as "sand." Such abrasive solids are undesirable for a number of reasons. For example, erode surface equipment and flowlines and sand in the production fluids can cut seals in well tools, such as safety valves and the like, as well as adversely affect pumping action of well pumps and the like.
In the past, those skilled in the art have attempted to abate such production of sand within the production fluids by "gravel packing" the well. This procedure customarily has entailed the introduction of a larger solid, such as bauxite, sintered bauxite, glass beads, or gravel or similar solids into a pumpable fluid, such as water, brine, polymeric gel, or the like, at the top of the well, through the well, and deposited exteriorly around a screen system carried on the production conduit. The solid particulate gravel-packing matter is deposited in an annular area that is defined between the exterior of the screen assembly and the interior of the subterranean wellbore. Upon a deposition of such gravel-packing solids within such annular area, the carrier fluid is pumped through the screen, through the well conduit to the top of the well and may be recycled therethrough by introduction of additional gravel-packing solid matter thereto, until the well is satisfactorily gravel packed, with or without a screen.
In the past, there have been some problems in the preparation of such gravel-packing systems as well as systems in which a solid is to be blended or otherwise prepared for introduction into the well by a carrier fluid for fracturing, cementing and other completion/workover operations. Thus, reference to "completion/workover systems" refers to gravel packing, fracturing, cementing fluids which combine one or more solids in a carrier fluid. Typically, such systems have been prepared by first preparing the carrier fluid in a tank, pit, or the like, adjacent the well and by introduction of the gravel or other solid thereto. A propeller mixer, or the like, may be used for the blending operations. A pump, such as a triplex pump, has been utilized to pump the prepared system including the carrier fluid and the particulate matter, from the tank or pit into the subterranean well.
However, such procedure has been found to have several disadvantages, including the fact that such procedure is time-consuming and because the preparation of "blending" operation is, in effect, performed in a tank, pit, or the like, away from the pump, dead spots will occur in flowlines used to transport the prepared system and the pump itself, resulting in deposition of the particulate matter, thereby hindering the placement of the particulate matter in the subterranean well.
The present invention addresses the problems set forth above and provides a method and apparatus which reduce the dead spots in the pump and flowlines and provide agitation of the particulate matter within the carrier fluid during the actual mixing or preparation operation. The elimination of the dead spots additionally provides a uniform distribution of the particulate matter in the carrier fluid.